The impact of nutrient pollution from phosphorus and nitrogen on the nation's waters is significant. The estimated annual cost of nutrient pollution in the United States in freshwater is greater than $2.2 billion. The U.S. Environmental Protection Agency (EPA) found that about 40% of stream miles in the United States had elevated phosphorus levels and 27% had elevated nitrogen levels. The National Centers for Coastal Ocean Science (NCCOS) has estimated that nutrient pollution has had a moderate to high impact in 65% of the coastal areas observed.
Phosphorus is required for life. Increasing human population is driving increasing demand for food, fiber, biofuel and other agricultural products. Phosphorus is a key soil nutrient in agriculture and is necessary to sustain plant and animal growth. Intensive agriculture requires the input and replacement of nutrient phosphorus, as crop harvesting removes soil phosphorus and food or fiber distribution transports it from the local ecosystem. Phosphate that is returned to soil as a fertilizer or other additive is mined from the Earth's finite phosphorus mineral reserves or replaced by land application of manures or treated human waste. The United States Geological Survey, Mineral Commodity Summaries, 2013, reported world phosphorus mine production and reserves at 67 billion tons, and there are concerns that global phosphorus demand will outstrip supplies within the next 50 to 200 years.